Whole-body cryotherapy is just what it sounds like: the whole body (minus the head) is exposed to ultra-cold temperatures. To do this, scientists have developed the CryoStar, which is a kind of tube-like chamber cooled by liquid nitrogen to a temperature between -225°F and -250°F. CryoStar users step into the chamber and the frigid temperatures instantly send the body into a natural fight or flight response. As blood vessels constrict, blood is redirected away from the extremities and toward the core in order to protect the organs. The body then becomes charged with oxygen and anti-inflammatory proteins, and excess white blood cells are flushed out, boosting the metabolic rate. 

After exiting the cryosauna, blood vessels dilate and rush oxygen-rich blood and endorphins back through the body. And then, in an effort to warm itself back to equilibrium, the body undergoes a metabolic reaction that can burn up to 800 calories in the hours proceeding treatment. Because these temperatures are actually colder than Antarctica in December, whole-body cryotherapy sessions only last 2-4 minutes.